Jiang Si had been learning painting from her master since childhood, so she immediately recognized the handwriting on the envelope as his.
Moreover, she knew it was written with his left hand.
However, she was utterly surprised by the fact that her master had suddenly written to her and even sent her something.
Although Mrs. Fang hadn’t explicitly stated where the master had gone, Jiang Si could roughly guess from the implications in her words.
Her master must have been temporarily assigned to a classified unit.
This could also be inferred from the encrypted mailing address.
With this in mind, Jiang Si quickly opened the envelope and skimmed through the letter.
"What does the letter say?" Huo Tingzhou noticed her grave expression, and a sense of foreboding rose in his heart.
Recalling the previous incident where Mrs. Fang had been assassinated by spies, he couldn’t help but frown.
"Is Professor Yu alright?"
"He’s fine. It’s not what you think."
Jiang Si took a deep breath, steadying her voice. "See for yourself."
Huo Tingzhou took the letter and quickly scanned it.
The contents were brief.
No pleasantries, no explanations.
It read:
[The components in the package must be drawn with the highest precision, including three-view diagrams (front, top, side), a 3D structural diagram, and detailed cross-sectional views of key parts.]
[During the drawing process, dimension lines must be marked, but no specific values are required. Scale: 1:1.]
[Once completed, seal and return to this mailbox.]
Had they not been so familiar with Professor Yu’s way of doing things, they might have suspected it was a prank.
While Huo Tingzhou read the letter, Jiang Si had already unwrapped the package her master had sent.
One bundle contained drawing tools.
Jiang Si glanced over them—these were clearly custom-made, unavailable on the market.
Beside them was a metal component wrapped in thick velvet.
About the size of a palm, its shape was somewhat intricate, covered in fine grooves and connectors.
"This must be a part from a rocket engine."
Huo Tingzhou had some knowledge in this area. He examined it carefully for a while.
"It connects to the centrifugal pump, but it’s an outdated foreign model."
"Outdated?"
Jiang Si was puzzled, but she felt there was more to it.
Completing such precise drawings would take at least a month.
Her master wouldn’t have sent her an obsolete part for no reason.
Could he be testing her skills on purpose?
Huo Tingzhou thought the same. After a moment of contemplation, a bold guess occurred to him.
"This time it’s an outdated model, but next time it might not be…"
Jiang Si: "You mean something currently in development?"
"Exactly." Huo Tingzhou nodded.
If he wasn’t mistaken, the rocket engine’s development was nearing completion.
To prevent leaks during production, all blueprints had to be hand-drawn.
They would then be sent to different military factories for manufacturing.
Finally, these components would be transported to the aerospace base in the capital for assembly.
Jiang Si’s task was to translate complex 3D mechanical structures into 2D blueprints, with errors kept within millimeters.
Otherwise, even the slightest flaw could lead to a failed launch.
After hearing Huo Tingzhou’s analysis, Jiang Si fell silent.
She paced back and forth in the living room several times before finally asking,
"Don’t you think something feels off?"
Huo Tingzhou stayed quiet, not wanting to interrupt her train of thought, and gestured for her to continue.
Jiang Si said, "Master went missing in ’63, meaning he’s been working on classified projects for over six years."
"If what you said is true, and the engine’s development is almost finished…"
"Then he could’ve drawn these himself."
"Why go out of his way to have me do it?"
As she spoke, she suddenly turned to look at him.
"Do you remember when Master started teaching me to draw mechanical diagrams like this?"
Huo Tingzhou nodded. "I do. You were eleven that year."
That was also the year he left the Jiang family.
Jiang Si pondered this. Of course, she knew when her master had taught her.
But at the time, she couldn’t understand it at all.
She remembered asking him why he’d suddenly shifted to making her draw such dull, technical things that semester.
Her master hadn’t explained much then, only saying, "More skills never hurt," and adding, "You’ll understand later."
Now, piecing everything together, Jiang Si felt a chill run down her spine.
Had her master already been assigned a secret mission back then?
Going even deeper—was it possible that from the moment he came to the Jiang family to teach her painting, he’d already planned to train her for this role?
"There’s one more thing—"
Jiang Si paused, her gaze falling on the envelope.
She picked it up, comparing it to the letter her master had written.
"I can’t figure out why he wrote this letter with his left hand."
As she spoke, a faint unease settled in her heart.
"Do you think… something might have happened to him?" she asked.
Huo Tingzhou had the same suspicion, but with no way to verify it, he could only reassure her gently.
"Don’t overthink it. The fact that Professor Yu could send you this letter at least means he’s not in immediate danger."
"As for the left-handed writing, I think he might just not want others to know who wrote it."
Jiang Si considered this and found his reasoning sound.
Even classified units weren’t entirely safe these days.
Hadn’t that spy managed to infiltrate a subsidiary of the Seventh Ministry for over eight years?
Seeing her expression ease slightly, Huo Tingzhou added,
"Professor Yu might simply be using this as an opportunity to train you. After all, he’ll have to retire someday."
Then he looked at her seriously. "Sweetheart, have you ever considered that after Professor Yu steps down, he might want you to take his place?"
Jiang Si: "Me?"
Huo Tingzhou nodded.
He gave his reasons.
"You’re Professor Yu’s only direct disciple."
"Even he has said your painting skills 'surpass the master.'"
Given these points, Huo Tingzhou believed it was highly likely.
Jiang Si had never thought about it this way, but his words did ease her worries somewhat.
For now, she couldn’t contact her master, so she’d take things one step at a time and focus on completing the task at hand.
Having sorted through her thoughts, her expression relaxed.
But the drawings didn’t need to be rushed. Jiang Si glanced at the pile of packages on the floor.
"Eldest Brother and Sister-in-law really went all out this time. We should send them some dried seafood in return."
Given the long distance to the remote frontier region, it was the most suitable gift.
"Alright, I'll follow your lead," Huo Tingzhou agreed without hesitation.
There wasn't much else he could assist with, so he focused on settling household matters, doing his best to spare his wife from unnecessary worries.
